The state of the art includes furnaces for direct reduction processes wherein hydrocarbons are injected into the current of reducing gas to allow the reaction of reforming the methane in the furnace with the H.sub.2 O and CO.sub.2 in the gas; there are also furnaces for direct reduction processes wherein hydrocarbons having C&gt;5 are injected directly into the furnace in the zone between the injection of reducing gas and the upper outlet of the exhaust gas.
The following patent documents disclose other different types of furnaces for direct reduction processes of mineral iron:
U.S. Pat. No. 3,749,386, U.S. Pat. No. 3,816,101, U.S. Pat. No. 4,046,557, U.S. Pat. No. 4,536,213, U.S. Pat. No. 4,752,329, U.S. Pat. No. 5,064,467, U.S. Pat. No. 5,078,788, U.S. Pat. No. 5,387,274, U.S. Pat. No. 5,407,460.
The state of the art also includes gravitational type furnaces, or shaft furnaces, with a vertical and gravitational flow of the material which is subsequently sent, with a closed system of pneumatic transport in an inert atmosphere, to the melting furnace.
The Applicant is not aware of any furnaces for the production of metal iron by means of direct reduction provided with a multiple outlet or star outlet which can encourage the simultaneous but differentiated discharge of several types of product.